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==Anomalous Septa==
==Anomalous Septa==

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I have decided to take early retirement in September 2020. During the many years online I have received wonderful feedback from many readers, researchers and students interested in human embryology. I especially thank my research collaborators and contributors to the site. The good news is Embryology will remain online and I will continue my association with UNSW Australia. I look forward to updating and including the many exciting new discoveries in Embryology!

Abbott ME. Congenital Cardiac Disease (1915) Osler & Mccrae's Modern Medicine 6, 2nd Edition.

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1915 Congenital Cardiac: Congenital Cardiac Disease | Heart Development | Literature | Etiology | Cyanosis | Classification | Pericardium | Heart Displacement | Whole Heart | Anomalous Septa | Interauricular Septum | Interventricular Septum | Absence of Cardiac Septa | Aortic Septum | Pulmonary Stenosis and Atresia | Pulmonary Artery Dilatation | Aortic Stenosis or Atresia | Primary Patency and Ductus Arteriosus | Aorta Coarctation | Aorta Hypoplasia | Diagnosis Prognosis and Treatment | Figures | Embryology History | Historic Disclaimer

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Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)

Anomalous Septa

Anomalous cords, bands, or septa may arise within the heart, and lead, when sufficiently pronounced, to a division of the chambers, and the so-called double or supernumerary cavities.

Anomalous Septa in the Left Auricle (Double Left Auricle). — Of this interesting condition there are eight fully reported cases, by Church (1868), Fowler, Martin, Griffith (2 cases). Potter and Ransom, Borst, and Hosch,^ all of which are summarized in an article by the latter writer. In these cases, a membranous diaphragm perforated by one or more openings stretches across the left auricle, dividing it into a right posterosuperior chamber, which receives the pulmonary veins and contains the interauricular septum, and a left antero-inferior chamber, in which lies the auricular appendix and the mitral orifice. The blood from the pulmonary veins enters the large upper chamber and passes thence through the small, opening in the diaphragm into the lower chamber to the mitral orifice. When the foramen ovale is patent, a large portion of the pulmonary blood may pass through the open foramen into the right auricle, thus depleting the greater circulation and throwing the bulk of the work on the right heart, which, as in this case, becomes greatly hypertrophied, and the left chambers very small.

Borst gives a careful anatomical study of his case, which throws much light on the etiology. In a woman, aged thirty-eight years, dying with failing compensation, the heart was of a quadrate shape, the right ventricle much hypertrophied and dilated, the left auricle also greatly dilated. There was no communication between the auricles, but the valvula formanis ovalis was absent. The left auricle was divided into a large upper cavity receiving the pulmonary veins and a small lower chamber containing the mitral orifice by a diaphragm which ran from above anteriorly and externally, downward, inward and backward. This diaphragm presented at its insertion below and behind, a round hole, 1 cm. across, which was the only communication between the two cavities through which the blood from the pulmonary veins could be transmitted to the mitral orifice.

Borst explained this anomalous diaphragm as the malposed septum primuvi which had been deflected to the left in the embryonic heart by a displacement of the pulmonary veins to the right, so that they entered the auricles between the septum primum and secundum, and had thus formed between them this large secondary cavity. The hole in this anomalous septum, which communicated with the smaller cavity below, he looks upon as the ostium secundum (patent foramen ovale).

1 Frankf. Zeitsch. f. Path., 1907, i, 56.

2 Verh. der XVI Deut. path. Gesell, 1913, p. 256.

Borst's explanation receives corroboration in a remarkable way from what may be termed a complementary case reported by Sternberg in which three auricular chambers were present, separated from each other by strong septa. The left chamber received the pulmonary veins and contained the mitral orifice, and communicated with the middle chamber by a large ovoid foramen (the ostium primum of Born), situated in the lower portion of the anomalous septum (S. primum) just above the mitral valve. This middle chamber received the superior cava only and communicated with the remainder of the right auricle, which received the inferior cava, by a large opening. Sternberg explained the formation of the middle chamber by a displacement to the right of the septum secundum, due to a malposition of the inferior cava, which entered too far to the left, and pushed the septum secundum to the right, just as in Borst's case the anomaly was due to the entrance of the pulmonary veins too far to the right, so that they cut off a middle chamber by pushing the septum primum to the left.

An anomalous band several cm. long and as thick as a knitting needle may traverse the left auricle. Cases were recorded by Browicz, Rolleston and Hosch.

Anomalous Septa in the Right Auricle. - These are quite different both in structure and origin from those in the left auricle. The condition was first described and figured by Chiari,^ on the basis of 11 original cases. In all these a system of fine cords, or a reticulum of delicate tissue identical in structure with the Eustachian valve and attached to this or to the Thebesian valve stretched across the auricle to be attached to the crista terminalis or auricular septum or other points. Similar structures in the right auricle have been recorded, and are to be ascribed, as Chiari pointed out, to a persistence and anomalous development of the septum spurium or of the right and left valvulse venosse. These are the lips of the opening of the embryonic sinus venosus into the right auricle. In normal development they become merged "^dth the Eustachian and Thebesian valves, and with the septum secundum. In a case by Lesieur and Froment^ of a gaping foramen ovale with an anomalous valve of Thebesius, 6 cm. high, which projected as a fenestrated, incompletely attached, shelf across the right auricle, these authors ascribe both anomalies to the maldevelopment of the valvida venosa sinistra, which failed to close in the foramen ovale by merging "^'ith the septum secundum. A connection between these two anomalies is further established in Ebbinghaus's case, in which Chiari's fenestrated network extended across the auricle from the Eustachian valve, and the interauricular septum showed fifteen small and two large perforations. Persistent left superior cava is also frequently associated.

Clinical Aspects. When uncomplicated by other defects, such septa may exist without giving any evidence of their presence. All the cases of double left auricle recorded were in adults, except that by Hosch. There are certain dangers, however. When the septum is strongly developed, it is liable to hamper the blood stream. Church's case, and Borst's, both died at thirty-nine years of failing compensation, and Borst's patient suffered from earliest youth from dyspnoea. Again the fine reticulum that occurs in the right auricle may supply a possible nidus for thrombotic processes, which may lead to pulmonary embolism and death. This happened in Chiari's first case, and thrombosis is related also by Thilo and Thorel.

1 Ziegler's Beitr., 1897, xxii., 1. 2 j^y^j^ Medical, 1911 , xcvi, 1045.

VOL. IV — 23

Anomalous Septa in the Ventricles. - These again have a very different origin from those in the auricles. The commonest form is a septum shutting off the conus from the sinus of the right ventricle, which probably represents arrest at an early stage in the development of the heart, explained by Keith as a "persistence of the lower bulbar orifice." Such septa have usually undergone much fibrous thickening, and have been ascribed b}^ many observers to inflammatory contraction, but in a case reported by Bohm all evidence of fibrosis was absent, and the conus was separated from the sinus by a simple muscular ridge. Two cases reported by Stephen Mackenzie^ of hearts showing "three ventricles," separated by incomplete septa, probably belong here.

In another type of anomalous septum, a rudimentary chamber giving off the pulmonary artery, or the (transposed) aorta is cut off from a common ventricle which receives both auriculoventricular orifices, by what appears to be the malposed and defective interventricular septum. This t}T)e is well illustrated by the Holmes specimen in the jMcGill Museum (described and figured under Triloculate Heart, page 373). There are eight similar cases in the literature, but in all except that of Holmes the aorta and pulmonary artery were transposed.

Anomalous chordae tendinece frequently cross the ventricles at irregular points. They may consist of fibrous tissue with or without ordinary heart muscle fibres, or they may contain fibres from the auriculoventricular bundle. These fibres have been studied by Tawara,^ who gives a review of the literature, and by Monckeberg.^ They are explained by the latter, as an irregular differentiation of the spongy musculature of the embryonic ventricle, which may or may not contain Pm-kinje fibres according to their distribution. Such abnormal chordae may cause loud musical murmurs. A case in point is related by Hamilton.^ The patient was a man of forty with symptoms of aortic insufficiency, who presented, in addition to a soft diastolic murmur with the localization characteristic of this lesion, a second murmur, also diastolic, but musical in character, which had its maximmn intensity at the third left interspace, but was widely propagated over the chest, and was so loud as to be audible two feet away from the patient. The autopsy, performed by Adami, showed this musical murmur to have been produced by an anomalous cord which sprang from a small papillary muscle of its own, and crossed the auricular surface of the aortic cusp. The aortic valves were thickened and incompetent.

Anomalous chordae passing from the aortic cusps to the base of the aorta (Rohrle), and from pulmonary cusp to base of pulmonary artery (Poscharissky) and from left kuricle to left ventricle through the mitral orifice, have been recorded.

^ Trans. Path Soc. Lond., 1880, xxxi, 63.

^ Ziegler's Beitr., 1906, xxxix, 563.

3 Verhand. XII Deut. Path. Gesell, 1908, p. 160.

  • Montreal Med. Jour., 1899, xxviii, 508.

(oscharissky) and from left kuricle to left ventricle through the mitral orifice, have been recorded.

Fig. 23

Aberrant chordae tendineae in left ventricle producing a loud musical diastolic murmur. (From a specimen in the McGiU Medical Museum, presented by W. F. Hamilton and J. G. Adami.)

Defects of the Interauricular Septum

These may consist of a simple patency of the foramen ovale, or true defects of the interauricular septum, situated above or below the foramen, and single or multiple, may occur. In this series, the foramen ovale was patent 192 times, and there were 46 true interauricular defects, of which 15 were in its upper and 18 in its lower part, and 13 were multiple. In 14 cases the septum was rudimentary and in 5 it was absent (cor biventriloculare) .

Patent Foramen Ovale. - This orifice, which in the fetus is widely open, allowing of the passage into the systemic circulation of aerated placental blood, usually closes after birth, but its persistence in adult life as a valvular slit is so common that this can scarcely be considered abnormal. Among 711 adults, Zahn found the foramen open in 139, and in Adami's records of 1374 autopsies at the Royal Victoria Hospital, Montreal, it occurred 199 times (14.5 per cent.). From the combined statistics of Bizot, Ogle, Klob, Wallman, Rostan and Hinze, we learn that among 2087 hearts examined, the foramen was patent 632 times (30 per cent.) (Herxheimer).

A widely patent foramen is, however, a true anomaly, which, by allowing free communication between the auricles, may give rise to various disturbances. Of the 191 cases in this series, 89 were of this type, and of these, 18 were instances of pure patency, unassociated with other defect, and were therefore classed as the primary lesson, as affording material for the study of special symptoms and signs. In some cases the opening is very large, the size of a "two-shilling piece" (Peacock), in others it is a "circular opening with thickened edges admitting a penhandle," and in others again, it is valvular in form but an elliptical gap remains between the concave free margins of the annulus ovalis and the valvula foraminis ovalis, which are here incomplete.

The causes of patency may lie in a rise of pressure in the right chamber after birth, preventing the firm apposition of the valvula foraminis ovalis from the side of the left auricle, and its subsequent closure; this is the case in the majority of the cases complicating other defects, such as pulmonary stenosis. Or the foramen may remain open as a result of a true arrest of growth of the primitive septa, especially of the septum secundum, an event which may be shown in the specimen by an incomplete development, absence, or fenestration of the annulus ovalis. The association of an anomalous network springing from the Thebesian or Eustachian valve, with a patent foramen or perforated valvula foraminis ovalis, and the dependence of both anomalies on the persistence of the embryonic sinus-valvular apparatus, has been mentioned. Persistence of the left superior vena cava belongs to the same complex, as is illustrated by its occurrence in the case of Berthel.

Such a combination is well illustrated in a remarkable case in the McGill Museum from the service of C. F. Martin. The patient was a woman of thirty-eight, presenting the symptoms of mitral stenosis with auricular fibrillation, and a greatly dilated heart. At the autopsy the mitral valve was markedly stenosed and the foramen was widely patent, a permanent elliptical opening 2.5 x 1.5 cm. large, with calcified lower border existing. The auricular septum behind this was greatly thinned and dilated and was bordered in the right auricle by a flattened and much fenestrated ring representing the defective annulus ovalis, and the Thebesian valve was enlarged and retiform. On the side of the left auricle at the right posterior margin of the septum, there was a curious valvular-looking pocket 2 cm. deep, the free margins of which were attached to the auricular wall by a plexus of tendinous cords. At the foot of this pocket a channel could be traced by a fine probe which communicated with the right auricle above the Eustachian valve. The coronary sinus and veins were hugely dilated.

Defects in the Upper and Posterior Part of the Interauricular Septum. - These are extremely rare. Two types may be distinguished, one in which the defect is associated with an anomalous disposition of the great veins, which is probably the primary condition, and another in which no such associated anomaly has been demonstrated, and which on closer investigation may be found to belong in the same category with the first, or which may require a different explanation. A series of cases has been recorded, in which a large defect occupies the upper margin of the auricular septum, directly under the orifice of the superior vena cava, which is displaced somewhat to the right, so that its orifice looks into both auricles through the defect. A displacement to the right of the pulmonary veins, so that these enter either the superior vena cava just before this vessel reaches the heart, or the right auricle itself, has been noted and is to be considered the primary anomaly. Paltauf thought that the hole in the septum was not a defect at all, but represented the orifice of the right pulmonary vein, which entered here directly above the septum, with the superior cava. In Hepburn's case the wall of the auricles was directly continuous with the wall of these two veins, which here entered the auricle together. The foramen ovale was patent in some cases, and is mentioned as closed in others.

Rokitansky described 7 cases of a similar anomaly, in which the inferior cava looked into both auricles through the defect. In one of these the right pulmonary veins entered the right auricle.

Fig. 24

Defect in the upper part of interauricular septum (persistent ostium secundum), with pulmonary dilatation, sclerosing pulmonary endocarditis with calcification, and hypoplasia of the aorta. From a woman, aged sixty-four years. Right chambers laid open to show: A, hypertrophied and dilated right auricle; B, large defect in the upper part of interauricular septum bounded below by C, a stout muscular partition, the defective auricular septum; D, absence of annulus ovaUs and of Eustachian valve; E, dilated coronary sinus guarded by a defective valve of Thebesius; F, entrance of superior vena cava; G, entrance of inferior vena cava. (From a specimen in the Medical Museum^ of McGill Univeristy, Montreal. Presented by F. W. C. MoFr. Eeporte*l by M. E. Abbott and J. Kaufmann.)

1 Jou7\ Path, and Bacteriol., 1910, xiv, 525.

In a specimen in the McGill Museum, reported by Abbott and Kaufmann^ (see Fig. 24), a large ovoid defect 3 x 3.5 cm. in diameter occupies the upper and back part of the septum, but the superior cava is not displaced, but enters the right auricle in its normal situation and is separated from the defect by a strong muscular cushion. The position of the right pulmonary veins could not be ascertained, but the annulus ovalis and Eustachian valve are absent, and it is probable that we are here dealing with an entirely different condition, namely, a huge persistent ostium secundum (patent foramen ovale) which has escaped closure through lack of development of the secondary septum. The heart was from a woman of sixty-four in good health until the last six years of life, wdien cyanosis began to manifest itself. The case terminated with failing compensation and profound cyanosis, and is further remarkable in that extensive endarteritic changes with extreme calcification had taken place in the pulmonary valves, as the result of the excess of work done by the pulmonary circulation.

Fig. 25

Heart sho-n-ing (A) defect of interaiiricular septum below (persistent ostium primum), with (B) cleavage of right anterior segment of mitral valve. (CO Interauricular septum above showing closed foramen ovale. (D) Left posterior mitral segment. From a woman, aged thirty-two years, without cardiac symptoms, dying of perforative appendicitis. (From a specimen in the Pathological Museum, McGill University.)

Defects in the Lower Part of the Interauricular Septum. — These are somewhat more frequent than are defects at the upper part of the septum, but are also rare. They are explained as a persistence of the ostium primum, the septum primum having failed to descend and unite with the cushion between the auriculoventricular orifice. Such a defect has a very characteristic appearance. It lies directly above the ventricles, may be of very large size, and is of a crescentic or semilunar shape, the thin border of the auricular septum, which forms its upper boundary, arching across the venous ostia to join the lower margin formed by the bases of the mitral and tricuspid valves, which are commonly deformed.

A common and interesting associated anomaly is a division of the anterior segment of the mitral valve, which is cleft from its free border up to its insertion, the two parts converging here to an acute angle, being widely separated below. In five of the seven cases of this defect reported by Rokitansky this cleavage occurred. It is well seen in Fig. 25, from a specimen in the McGill Museum. Here the foramen ovale was closed, as in the cases reported by Griffith,^ Soldner,^ Moore,^ and Peacock.'* It was patent in the cases by Reineboth,^ Thomson," Kilduff e,^ and Sternberg.^

Multiple Defects. - The valvula foraminis ovalis is not infrequently perforated by numerous small openings, as in a specimen (Fig. 26) in the McGill Museum, and in several cases in this series. This recalls the fenestrated septum seen in birds, and suggests an arrest of development at this stage. In a case reported by Dublitzhaja, of combined defects of the auricular and ventricular septa, the auricular septum, defective below, "hung like a curtain over the common ventricle," there was a large patent foramen ovale, and also a large hole at the upper and posterior border of the valvula foraminis ovalis. An almost identical case is reported by Ebbinghaus. In a man of fifty-two, there were fifteen small perforations and two large holes at either border, representing the persistent ostium primum and secundum (patent foramen ovale), and the right auricle contained an anomalous network.

Aneurismal Pouching. - Aneurismal pouching of the fossa ovalis is sometimes seen (Figs. 26 and 27). In most cases the convexity of the pouch is toward the left auricle, indicating a rise of pressure in the right heart before death.

Secondary Pathological Changes. - The alterations in the circulation produced by large defects in the interauricular septum induce various secondary results. Hypoplasia of the aorta and a corresponding dilatation of the pulmonary artery are common, and the latter vessel may also be atheromatous from excessive strain. Hypertrophy and dilatation of the heart are the rule, and this may be confined to the right chambers or may be generalized, the changes in the right side almost always preponderating. In none of the cases in this series was the left ventricle hypertrophied in excess of the right. Both auricles are usually much dilated and in four of our cases this took place without any increase in size of the ventricles. Congestive changes and oedema of the lungs, enlargement of the liver, and passive congestion of all organs usually occur as late results of the overloading of the pulmonary circulation.

1 Manch. Med. Chron., 1902, iv, 383. _ ^ Munich Thesis, 1904.

^ Trans. Path. Soc, London, 1881, xxxii, 37.

4 Ibid., 1847, i, 61.

5 Deut. med. Woch., 1895, xxi, 870. « Proc. Anat. Soc, 1902-3, xxxvi.

7 Am. Jour. Med. Sc, 1914, cxlvii, 880.

8 XVI Verh. d. Deut. GeselL, 1913, p. 253

Fig. 26

Fenestrated membrane bulging into fossa ovalis. (From a specimen in tlie Fatliological Museum, McGill University.)

Fig. 27

Bulging of fossa ovalis into left auriclo. Valvular patent foramen ovale. (From a specimen in the McGill Pathological Museum.)

Symptoms and Signs. - Large defects in the interauricular septum may exist Vv'ithout giving any sign or symptom of their presence and without interfering with the duration of life of the individual. The characteristic feature of the majority of the cases may be summed up as an absence or but very slight manifestation of cyanosis, in the presence of distinctive physical signs of the defect. In a few rare instances, symptoms of congenital cyanosis have set in, in cases of uncomplicated foramen ovale in very early life. There are three such in our series, one by Johnson, of a man aged twenty-seven with moderate cyanosis and slight clubbing, and the others by Simmons^ and Foster^ in infants, showing cyanosis and dyspnoeic attacks.

The above statement is especially true of defects at the upper part of the septum. All the patients in this series reached middle life without giving any evidence of disease, and with the exception of two cases, all died of independent conditions unassociated with the defect. In Greenfield's case, a man, aged fifty-three years, failing compensation set in eighteen months before death and cyanosis was marked at the close.

Not infrequently symptoms first develop after some event, such as an intercurrent pneumonia, has embarrassed the pulmonary circulation, and thus caused a rise of pressure in the right auricle, followed by a passage of venous blood from right to left through the defect. The picture is usually that of a relative mitral insufficiency, with marked cyanosis supervening as a terminal event. These are the cases of la cyanose tardive described by Bard and Curtillet as characteristic of auricular septal defects. The hypoplasia of the aorta so often associated with patent foramen probably assists in the development of failing compensation, and therefore forms an essential part of the picture.

Auricular septal defects are not infrequently associated with mitral stenosis. Such cases, of which there are seven in our series, usually run their course under the guise of the complicating mitral condition, the defect probably adding a factor in the development of the cardiac distress. An example of the absence of characteristic symptoms in extensive communication between the auricles is seen in Dr. Martin's case of mitral stenosis with open foramen. The clinical picture here was that of the terminal stages of uncomplicated mitral stenosis, and the degree of cyanosis was not greater than might have been expected in such a condition. A presystolic thrill with maximum intensity at the left fourth interspace, and a presystolic murmur audible towards the base which disappeared as the end approached, were the only evidence of the defect.

1 Inter. Med. Jour. Austr., Feb. 20, 1906.

^ Dublin Quarterly Jour. Med., 1863, xxxvi, 112.

Pallor of the surface is a common characteristic (Mouls^ as is also a certain delicacy of build, the result evidently of the diminished amount of blood in the systemic circulation. Dyspnoea and tachycardia, bronchitis and signs of congestive changes in the lungs and of passive congestion in the viscera and enlargement of the liver are also common, from excess of blood entering the right heart. When, in adults with these symptoms, and with cyanosis slight, absent, or of extremely late appearance, we find distinctive physical signs of a defect localized over the upper and middle thirds of the heart, we may feel fairly sure that we are dealing with an auricular septal defect. A correct diagnosis was made on this basis in a patient at the Royal Victoria Hospital whose heart is in the McGill Museum. In a woman of twenty-eight years, of somewhat infantile appearance, in whom cyanosis was entirely absent, a loud harsh systolic murmur with maximum intensity at the third left interspace, 4.5 cm. from the midsternum, was heard loudly all over the front of the chest and over the left back, the cardiac dulness was greatly increased in all directions, and there was a marked systolic thrill at the base to the left of the midsternum, extending downward to the top of the fourth rib. The neck veins were much distended, but no positive venous pulse was detected. Death occurred from chronic interstitial nephritis. The autopsy showed a large patent foramen ovale admitting the thumb, with cribriform perforation of the valvula foraminis ovalis, hypoplasia and slight coarctation of the aorta, and infantile genitalia.

The slight degree of cyanosis that characterizes these cases and the effect of the lesion upon the duration of life are well shown by the analysis of the 43 cases of auricular septal defects classified as the primary lesion in this series. Cyanosis was entirely abse?it in 21 cases. In 2 of these death apparently due to the defect occurred in 4, in 2 cases from failing compensation, in 1 from sudden collapse, and in 1 (Popper^) by sudden development of oedema and dyspnoea. Terminal cyanosis occurred in 13 cases of the series. The ages of the patients ranged from ten to sixty-four years, and death ocurred from pneumonia in 2, from failing compensation in 6, and from cerebral hemorrhage in 1 (Ebbinghaus) . In 4 other cases of the 43, cyanosis was described as slight and in 3 only as moderate (Johnson, Foster, Simmons).

Physical signs are sometimes absent, but, in widely patent foramen ovale, and in defects at the lower part of the septum, a sufficiently characteristic murmur is usually present, and sometimes a corresponding precordial thrill. In defects at the lower part of the septum in which extensive deformities of the auriculoventricular cusps are usually associated, the murmur produced is often heard best at the apex, and is "confused," or " roaring" in character. It was associated in 4 out of 10 cases analyzed with a thrill continuous or systolic or "presystolic" in rhythm. In widely patent foramen, the murmur is usually systolic or presystolic and is sometimes soft, but often harsh and rasping, or of a peculiar blowing, or even musical character, and may be localized in the second, third or fourth mterspace near the left sternal border, or over the midsternum in this situation, or may be diffusely heard over the precordium. It is frequently audible in the left back, and may be transmitted to the apex and axilla, or (occasionally) to the left subclavicular region (Markham's'case), or may be heard loudly over the whole chest. Among the 18 cases of patent foramen analyzed, a murmur of the above character was noted in 14. In 9 it was systolic, in 3 presystolic, in 2 it varied from presystolic to systolic, and in 1 only (Bard and Curtillet) it was diastolic in rhythm. In 3 of these cases the murmur was associated with a thrill of corresponding localization and rhythm.

1 Rev. Mens, des Mai. des Enfant, 1888, vi, p. 151.

2 Wien. klin. Woch., 1909, No. 16, p. 562.

Both murmur and thrill may vary in intensity and in rhythm with the position of the patient being noted as presystolic or systolic on different examinations. This inconstancy may be a useful diagnostic point (Ohm).

When an organic mitral insufficiency is combined with a patent foramen, the regurgitation of blood through the defect into the right auricle during systole of the ventricles may give rise to a positive venous pulse in the neck, without the presence of tricuspid insufficiency. Cases are reported, confirmed by autopsy, in which the tricuspid was healthy, and in which no signs of tricuspid regurgitation existed during life. When mitral stenosis is present this sign is of no value, as it is likely to be due to the auricular fibrillation so frequent in this condition.

Paradoxical Embolism. - A serious clinical significance is given to patent foramen ovale by the fact that particles may be carried through the defect from the venous circulation to the arteries of the brain, or from the systemic arteries to the lung, leading to instant death. This possibility was first pointed out by Cohnheim in an observation of a woman dying of embolism of the middle cerebral artery. The foramen admitted three fingers, the arterial system was clear, while the primary thrombi lay in the veins of the lower extremities. Ohm^ collected 11 such cases from the literature in which an embolus from a thrombosed vessel or a metastasis from a new growth undoubtedly passed through the open foramen and added an original case. Ballet^ collected 6 cases of death from cerebral abscess from infected emboli in which both cardiac and cerebral symptoms were present during life. In 3 of these there was a patent foramen, in 2 a defect of the interventricular septum. Verse* described 2 typical cases.